Showing papers on "Photonic-crystal fiber published in 2021"
TL;DR: In this paper, the photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor for early detection of malaria disease in humans by measurement of the variation of red blood cells (RBCs).
Abstract: This article presents the photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor for early detection of malaria disease in humans by measurement of the variation of red blood cells (RBCs). In the proposed PCF, two layers of air holes are arranged in a hexagonal lattice structure and a thin film of gold-coating is used over PCF for the occurrence of SPR phenomena. It occurs when surface plasmon polariton (SPP)-mode coupled with the core-mode during phase-matching conditions. Malaria infected RBCs samples are filled into the PCF, which have own refractive index (RI) that shift the SPR resonance wavelength during confinement loss measurement. The resonance wavelength of malaria-infected RBCs samples is different from their normal RBCs samples due to the difference in RI of infected and normal RBCs samples. The proposed work is helpful in the detection of different stages of malaria-infected RBCs such as ring phase, trophozoite phase and Schizont phase by measuring the shift in resonance wavelength. The calculated wavelength sensitivities of the proposed sensor for the ring phase, trophozoite phase and Schizont phase RBCs are 13714.29 nm/RIU, 9789.47 nm/RIU, and 8068.97 nm/RIU, respectively in x-polarized direction and 14285.71 nm/RIU, 10000 nm/RIU, and 8206.9 nm/RIU, respectively in y-polarized direction with the maximum detection limit of 0.029. The proposed PCF-based SPR biosensor is suitable for the early diagnosis of malaria disease due to its enhanced sensing performance (low detection limit and high sensitivity).
113 citations
TL;DR: In this article, an asymmetrical arrangement of rectangular holes where the core region is composed of a single rectangle is used as the fiber substance for detecting blood and skin cancerous cells using PCF-based sensor.
Abstract: This paper reports a novel approach for the efficient detection of blood and skin cancerous cells using PCF-based sensor. The proposed sensor contains an asymmetrical arrangement of rectangular holes where the core region is composed of a single rectangle. Zeonex is used as the fiber substance. The model is structured and numerically analyzed using the finite element method (FEM)-based software. The simulation of the proposed model validates its efficiency in cancer cell detection. Several performance parameters suggest that the proposed sensor attains optimum results at 2.0 THz. At this point, the sensitivities achieved in detecting blood cancer cells, normal cell (Jurkat), skin cancer cell, normal cell (basal), and water are 96.74, 96.56, 96.61, 96.34, and 95.69%, respectively. Besides, simulation results also suggest that the material and confinement loss are very low for this proposed sensor. Additionally, the simple rectangle-based model provides the ease of fabrication introducing prevailing strategies.
109 citations
01 Mar 2021-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this article, an extremely high sensitive and nonlinear chemical sensor based on photonic crystal fiber is presented with numerical investigation, in order to reduce fabrication complexity, the proposed chemical detector is designed with circular air holes.
Abstract: This study has reported an extremely high sensitive and nonlinear chemical sensor based on photonic crystal fiber is presented with numerical investigation. In order to reduce fabrication complexity, the proposed chemical detector is designed with circular air holes. To calculate the guiding characteristics, finite element method based Comsol software is used. Different types of commonly used materials are used as background material of that proposed sensor to ensure maximum relative sensitivity to the chemicals. The simulation results confirms that, very high relative sensitivity of 97.89%, 96.31%, 91.87% and 88.93% for benzene, chloroform, ethanol and water respectively at 1.55 µm of optical signal. Moreover the proposed chemical sensor offers negligible confinement loss of around 10–10 dB/m for all sensing analytes. In addition, other important characteristics such as numerical aperture, nonlinearity are discussed in detail. The wavelength dependent light guiding characteristics for the solid materials and the sample under test is used in simulation to ensure better accuracy and to create real life environment.
101 citations
TL;DR: In this paper, a photonic crystal fiber (PCF)-based, hollow-core, optical waveguide is proposed and numerically investigated to quickly identify numerous species of cancerous cells in the human body.
Abstract: A new photonic crystal fiber (PCF)–based, hollow-core, optical waveguide is proposed and numerically investigated to quickly identify numerous species of cancerous cells in the human body. Typical and cancerous cells have different refractive indices (RIs), and via this characteristic, the other important optical parameters are evaluated. The guiding properties of this proposed cancer cell sensor are analyzed in the COMSOL Multiphysics environment which used the finite element method as mathematical tool to solve differential equations. Furthermore, to ensure the highest simulation accuracy, extremely fine mesh elements are introduced. The simulation studies confirm that the proposed sensor, at 2.5 THz, achieves an extremely high relative sensitivity of almost 98% with negligible loss (< 0.025 dB/cm). Furthermore, a high numerical aperture (NA) and spot size, with low modal area, enhance the propagation characteristics of the sensor to a new height. The sensor’s physical structure is very simple so that it can be easily fabricated with modern fabrication technology. Thus, it seems that this sensor will open a new door in the field of detecting and diagnosing different cancer cells.
72 citations
TL;DR: In this paper, a simple designed photonic crystal fiber (PCF) sensor was proposed for detecting malarial infection using the refractive index (RI) of red blood cells (RBCs).
Abstract: Malaria is a mosquito-borne disease caused by unicellular hemoparasites of the genus Plasmodium that results in the death of over one million people worldwide every year. Early diagnosis plays a key role in the treatment of infected patients and can reduce the mortality rate. This work proposes a simple designed photonic crystal fiber (PCF) sensor for detecting malarial infection using the refractive index (RI) of red blood cells (RBCs). The initial structure of the PCF sensor consists of double loops of circular air holes arranged in a hexagonal formation. A horizontal elliptical channel in the center of the fiber contains the RBCs sample. The sensor’s response was observed from the shift of the transmission spectra due to change in the RI of RBCs during different life stages of the parasite. Model parameters (transmission length, pitch, air hole diameter, and eccentricity of the elliptical channel) of the proposed sensor were optimized to obtain the best possible response. The highest spectral sensitivities were obtained about 11,428.57 nm/RIU, 9473.68 nm/RIU, and 9655.17 nm/RIU for the ring, trophozoite, and schizont phases of the parasite, respectively. Due to its high sensitivity, easy identification capability, and short transmission length, this sensor can be utilized as a cost-effective and useful device for malaria diagnosis.
68 citations
TL;DR: In this article, a plasmonic material-coated circular-shaped photonic crystal fiber (C-PCF) sensor was proposed to explore the optical guiding performance of the refractive index (RI) sensing at 1.7-3.7 μm.
62 citations
TL;DR: In this article, a hollow core photonic crystal fiber is suggested and analyzed for the identification of different blood components present in human blood for better sensing applications, and the suggested fiber is numerically analyzed in terahertz frequency spectrum from 1.5 to 3 THz to obtain higher relative sensitivity (RS) and NA as well as lower absorption loss and confinement loss (CL).
Abstract: Hollow core photonic crystal fiber is suggested and analyzed in this article for the identification of different blood components present in human blood. In order to visualize the fiber and investigate the performance of that sensor based on COMSOL simulation software, the suggested fiber is numerically analyze in terahertz frequency spectrum from 1.5 to 3 THz to obtain higher relative sensitivity (RS) and NA as well as lower absorption loss and confinement loss (CL) for better sensing applications. The reported hollow core fiber provides better interaction of light and the analytes, so that extremely high RS is achieved at a particular geometric condition. Furthermore, extremely low CL and effective material loss (EML) with high numerical aperture (NA) can be achieved from the suggested sensor which paves the way to apply the fiber in numerous biomedical applications.
61 citations
TL;DR: In this paper, a two-dimensional photonic crystal fiber based on the surface plasmon resonance (SPR) refractive index sensor has been demonstrated and designed which is so much helpful to gain a better sensitivity response in urine observation.
57 citations
TL;DR: In this paper, an ultra-wide detection range refractive index sensor based on surface plasmon resonance (SPR) with photonic crystal fiber (PCF) is designed and discussed.
Abstract: An ultra-wide detection range refractive-index sensor based on surface plasmon resonance (SPR) with photonic crystal fiber (PCF) is designed and discussed. The central air-hole of the fiber is injected with the analyte. The properties of refractive-index sensor are investigated with different structure parameters. Simulation results show that the proposed sensor has an ultra-wide detection range from 1.29 to 1.49. The refractive index sensitivities of x-polarized and y-polarized core mode are −4156.82 nm/RIU and −3703.64 nm/RIU respectively, and the corresponding linear fitting degrees are 0.99598 and 0.99236. The designed refractive-index sensor with ultra-wide detection range has a great potential in the fields of biology, chemistry, environment and medicine.
55 citations
TL;DR: In this article, the current status of photonic crystal fibers (PCF) sensors based on surface plasmon resonance (SPR) is summarized, and simulation methods for PCF-SPR sensors are described.
Abstract: Optical fibers have been widely applied to telecommunication, imaging, lasers, and sensing. Among the different types of fibers, photonic crystal fibers (PCFs), also called microstructured optical fibers, characterized by air holes arranged along the length of fibers have experienced tremendous advance due to their unique advantages. They are regarded as a desirable platform to excite surface plasmon resonance (SPR) because of easy realization of phase matching conditions between the fundamental core mode and the plasmonic mode, which plays a critical role in miniaturization and integration of SPR sensors. In this mini-review, the current status of PCF sensors based on SPR is summarized. The theory of SPR is discussed, and simulation methods for PCF-SPR sensors are described. The important parameters including the refractive index detection range, resonance wavelength, and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors are reviewed. The fabrication and the comparison of performances are also illustrated, and, finally, the challenges and future perspectives are outlined.
51 citations
TL;DR: In this paper, a high sensitivity triple layer photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is proposed for RI analytes sensing, which assists to achieve high sensitivity, larger birefringence, maximum resolution and high transmittance profile.
TL;DR: In this paper, a simple hollow core hexagonal structured photonic crystal fiber is offered and analyzed to discern commonly used different type of alcohols in our daily life, the proposed sensor guiding properties are numerically investigated using a full vectorial finite element software-based scheme.
Abstract: In this study, a simple hollow core hexagonal structured photonic crystal fiber is offered and analyzed to discern commonly used different type of alcohols in our daily life. The proposed sensor guiding properties are numerically investigated using a full vectorial finite element software-based scheme. To ensure higher accuracy, the properties of alcohols (refractive index and dielectric constant) at different wavelength are used to calculate the behaviour of the sensor. The simulation results ensure that extremely high relative sensitivity around 89% can be achieved from the sensor at optimum structural condition. In addition, other important propagation parameters such as confinement loss (CL), single-mode propagation spot size, numerical aperture, etc., are discussed in detail for various geometric conditions. The structure of that sensor is straightforward, and available commercial fabrication technology can be used to fabricate it without any complexity.
TL;DR: In this paper, a strain sensor based on cascaded Sagnac loops with two polarization-maintaining photonic crystal fibers (PMPCFs) has been experimentally demonstrated.
Abstract: A strain sensor based on cascaded Sagnac loops with two polarization-maintaining photonic crystal fibers (PMPCFs) has been experimentally demonstrated. Air holes distributed on the cross section of PMPCF go through the whole fiber, which makes the special fiber more sensitive to ambient force compared with conventional optical fiber. The lengths of the two PMPCFs are close, but not the same, to form envelopes on the total output spectrum and then obtain high resolution to the detected parameter by the Vernier effect. The influences of the difference in length of the two PMPCFS on spectral envelopes are discussed. As the length of the PMPCF in reference loop increases, free spectrum range of the cascaded Sagnac loops (or envelope period) and magnification decrease. The sensitivities of this strain sensor are calculated by tracking upper and lower envelopes. Results reveal that its average sensitivity is up to 45.15 pm/ $\mu \varepsilon $ and the corresponding resolution is $0.44~\mu \varepsilon $ as strain varies from 0 to $2000~\mu \varepsilon $ . Compared with a single Sagnac loop, the sensitivity magnification is about 28.94. The sensing characteristics of a conventional polarization-maintaining fiber (PMF) are studied to compare with the PMPCF. Moreover, reversibility has also been proved to possess low error rate. In short, the fiber strain sensor possesses high sensitivity and great reversibility.
TL;DR: In this paper, a review of recently developed distributed and quasi-distributed POF-based sensing techniques based on Rayleigh scattering, Brillouin scattering, and fiber Bragg gratings is presented.
Abstract: Aging degradation and seismic damage of civil infrastructures have become a serious issue for society, and one promising technology for monitoring their conditions is optical fiber sensing. Glass optical fibers have been predominantly used for the past several decades to develop fiber sensors, but currently polymer or plastic optical fibers (POFs) have also been used extensively to develop advanced fiber sensors because of their unique features, such as high flexibility, large breakage strain, and impact resistance. This review focuses on recently developed distributed and quasi-distributed POF-based sensing techniques based on Rayleigh scattering, Brillouin scattering, and fiber Bragg gratings.
TL;DR: In this paper, an optical fiber surface plasmon resonance (SPR) biosensor was developed for measuring time and concentration-dependent DNA hybridization kinetics, achieving a sensitivity of up to 4461nm/RIU.
Abstract: In the present study, an optical fiber surface plasmon resonance (SPR) biosensor was developed for measuring time- and concentration-dependent DNA hybridization kinetics. Its design complies with a 3D Au/Al2O3 multilayer composite hyperbolic metamaterial (HMM), a graphene film, and a D-shaped plastic optical fiber. According to the numerical simulation and the experimental demonstration, the SPR peak of the designed biosensor can be effectively altered in the range of visible to near-infrared by varying the HMM structure. The sensitivity of the appliance was shown to achieve a value of up to 4461 nm/RIU, allowing its applicability for bulk refractive index sensing. Furthermore, a biosensor designed in this work displayed high-resolution capability (ranging from 10 pM to 100 nM), good linearity, and high repeatability along with a detection limit down to 10 pM, thus suggesting a vast potential for medical diagnostics and clinical applications.
TL;DR: In this article, a femtosecond laser point-by-point (PbP) technology was used to construct high-temperature-resistant UWFBG arrays.
Abstract: Ultra-weak fiber Bragg grating (UWFBG) arrays are key elements for constructing large-scale quasi-distributed sensing networks for structural health monitoring. Conventional methods for creating UWFBG arrays are based on in-line UV exposure during fiber drawing. However, the UV-induced UWFBG arrays cannot withstand a high temperature above 450 °C. Here, we report for the first time, to the best of our knowledge, a new method for fabricating high-temperature-resistant UWFBG arrays by using a femtosecond laser point-by-point (PbP) technology. UWFBGs with a low peak reflectivity of ∼ - 45 dB (corresponding to ∼ 0.0032%) were successfully fabricated in a conventional single-mode fiber (SMF) by femtosecond laser PbP inscription through fiber coating. Moreover, the influences of grating length, laser pulse energy, and grating order on the UWFBGs were studied, and a grating length of 1 mm, a pulse energy of 29.2 nJ, and a grating order of 120 were used for fabricating the UWFBGs. And then, a long-term high-temperature annealing was carried out, and the results show that the UWFBGs can withstand a high temperature of 1000 °C and have an excellent thermal repeatability with a sensitivity of 18.2 pm/°C at 1000 °C. A UWFBG array consisting of 200 identical UWFBGs was successfully fabricated along a 2 m-long conventional SMF with an interval of 10 mm, and interrogated with an optical frequency domain reflectometer (OFDR). Distributed high-temperature sensing up to 1000 °C was demonstrated by using the fabricated UWFBG array and OFDR demodulation. As such, the proposed femtosecond laser-inscribed UWFBG array is promising for distributed high-temperature sensing in hash environments, such as aerospace vehicles, nuclear plants, and smelting furnaces.
TL;DR: In this paper, a porous core dispersion flatten photonic crystal fiber (PCF) was modeled for the fruitful transmission of THz signals, and the model comprises only rectangular holes in both core and cladding areas.
Abstract: We present the modeling of a porous core dispersion flatten photonic crystal fiber (PCF) for the fruitful transmission of THz signals. The model comprises only rectangular holes in both core and cladding areas. The model is numerically studied through simulation employing the finite element method (FEM)-based software. Simulation results disclose an insignificant amount of confinement loss (CL) of 8.01 × 10–5 cm−1 at 1.1 THz in the x-polarization mode. Besides, the effective material loss (EML) is only 2.2 × 10–3 cm−1 at the point. These values ensure a negligible amount of losses present at the modeled waveguide. The model offers a high numerical aperture. The power fraction for this model is 45% in the x-polarization mode at 1.1 THz. One of the splendid properties of the presented model is the ultra-flatten dispersion of approximately ± 0.004 ps/THz/cm, which ensures an insignificant amount of pulse broadening while applying this model in communication fields. The simple structure involving rectangles as well as desired values for optical parameters enhance the fruitfulness and fabrication feasibility of the presented THz waveguide. Thereby, the proposed sensor offers compound features, for instance, low CL, low EML, high NA, high power fraction, and flatten dispersion simultaneously.
TL;DR: In this article, the transmission characteristics of a side-polished eccentric photonic crystal fiber (PCF) were studied by using the full-vector finite element method (FV-FEM).
Abstract: The transmission characteristics of a side-polished eccentric photonic crystal fiber (PCF) is studied by using the full-vector finite element method (FV-FEM). The proposed structure is composed of air holes similar to a U-shaped arrangement, and there is a small air hole between the side polishing plane and the core region to enhance the leakage of the evanescent field in the y polarization direction. It integrates refractive index (RI) sensing and polarization filtering. The RI sensing mainly works in the visible light band, while polarization filtering is suitable for the near-infrared band. The maximum sensitivity of the sensor is 12,500 nm/RIU, and the resolution is 8.0 × 10−6 RIU in the detection RI range of 1.35–1.39. By changing the external RI or the thickness of the gold-coated film, the bandwidth-tunable PCF polarization filter with excellent performance can be obtained. Therefore, the design of side-polished PCF will be of great significance to the development of integration and miniaturization of optical devices.
TL;DR: In this article, the spectral interrogation and amplitude methods were used to detect the refractive index (RI) variations of cancer cells, which varied from 1.392 to 1.401 for six different types of cancerous cells.
Abstract: In this study, early cancer detection of a single living cell is investigated by employing a surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) biosensor structure. The full-vectorial finite element method (FV-FEM) with perfectly matched layers are engaged for numerical analysis. The spectral interrogation and amplitude methods are used to detect the refractive index (RI) variations of cancer cells. The refractive index (RI) varied from 1.392 to 1.401 for six different types of cancerous cells. Obtained numerical results have indicated that, the highest sensitivities for spectral interrogation and amplitude methods are reported as 7142.86nm/RIU for MCF-7, and $$-757 RIU^{- 1}$$
for Hela cell, respectively.
TL;DR: In this paper, a combination of five layers spherical shape in cladding area with two layers of same circular shape in rotated-hexa core based decagonal photonic crystal fiber (D-PCF) was proposed for chemical finding in the terahertz (THz) ranges.
Abstract: In this research work, we have proposed an excellent work combination of five layers spherical shape in cladding area with two layers of same circular shape in rotated-hexa core based decagonal photonic crystal fiber (D-PCF) and explicated the simulation outcomes for chemicals finding in the terahertz (THz) ranges. The finite element method (FEM) and perfectly matched layers (PML) boundary complaint based on COMSOL Multiphysics has been cast off to design this structure with proper numerical parameters. After the numerical analysis, this fiber shows the high relative sensitivity are 78.56%, 79.76% and 77.51% and low confinement losses are 5.80 × 10−08, 6.02 × 10−08 dB/m and 5.74 × 10−08 dB/m for three chemicals such as Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330), respectively at monitoring region of 1 THz. Moreover, other optical properties such as effective mode index (EMI), effective area (EI), the total power fraction (TPF) are highly deliberated with their necessary graphical results. So, it is clearly seen that our suggested decagonal photonic crystal fiber (D-PCF) will be more appropriate in industrial areas and bio-medicine areas for chemical sensors especially, gas sensors to find potential applications in hospitals, industries and also for environmental monitoring.
TL;DR: In this paper, a heptagonal cladding with the rotated-hexacore (RH) in photonic crystal fiber (H-PCF) has been made for the field of chemical sensing in the terahertz (THz) area.
Abstract: A heptagonal cladding (HC) with the rotated-hexacore (RH) in photonic crystal fiber (H-PCF) has been made for the field of chemical sensing in the terahertz (THz) area. There are five layers of circular air holes (CAH) in the heptagonal cladding region and two layers of rotated-hexa of CAH in the area of the core that have been second hand to enterprise this PCF. This suggested H-PCF, a full-vectorial finite element method (FEM) and perfectly matched layers (PML) boundary condition has been utilized based on a software instrument. After simulation results, the proposed sensor displays the relative sensitivity (RS) 68.48%, 69.20%, 66.78% and the confinement losses (CL) are 2.13 × 10−09 dB/m, 1.92 × 10−09 dB/m and 2.70 × 10−06 dB/m for focused analytics Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330) independently at 1 THz frequency regime. We have also discussed total power fraction, effective mode index, and effective area elaborately here. However, our proposed H-PCF is suitable for the user such as in chemical sensors as well as in many diverse industrial and medical areas.
TL;DR: In this paper, low-loss optical fiber joints are a prerequisite in all-fiber devices Joining structurally dissimilar fibers, such as microstructured optical fibers, is a timely challenge, as they are beco
Abstract: Robust low-loss optical fiber joints are a prerequisite in all-fiber devices Joining structurally dissimilar fibers, such as microstructured optical fibers, is a timely challenge, as they are beco
20 Apr 2021
TL;DR: In this article, the authors exploit light-gas-acoustic interaction in a gas-filled anti-resonant hollow-core-fiber (AR-HCF) to demonstrate photoacoustic Brillouin spectroscopy (PABS).
Abstract: Photoacoustic spectroscopy, a powerful tool for gas analysis, typically uses bulky gas cells and discrete microphones. Here we exploit light-gas-acoustic interaction in a gas-filled anti-resonant hollow-core-fiber (AR-HCF) to demonstrate photoacoustic Brillouin spectroscopy (PABS). Pump absorption of gas molecules excites the acoustic resonances of the fiber, which modulates the phase of a probe beam propagating in the fiber. Detection of the phase modulation enables spectroscopic characterization of gas species and concentration as well as the fiber microstructure. Studying the acoustic resonances allows us to characterize the longitudinal inhomogeneity of the fiber microstructure. By tuning the pump modulation frequency to a wine-glass-like capillary mode of a 30-cm-long AR-HCF and the pump wavelength across a gas absorption line, we demonstrate detection of acetylene at the parts-per-billion level. PABS has great potential for high sensitivity gas sensing and non-invasive fiber characterization.
TL;DR: In this paper, the authors demonstrate an efficient and reliable fusion splicing method to achieve low-loss connection between a NC-HCF and a conventional single-mode fibers (SMF) by controlling the mode field profile of the SMF with a two-step reverse-tapering method.
Abstract: Negative curvature hollow-core fibers (NC-HCFs) can boost the excellent performance of HCFs in terms of propagation loss, nonlinearity, and latency, while retaining large core and delicate cladding structures, which makes them distinctly different from conventional fibers. Construction of low-loss all-fiber NC-HCF architecture with conventional single-mode fibers (SMFs) is important for various applications. Here we demonstrate an efficient and reliable fusion splicing method to achieve low-loss connection between a NC-HCF and a conventional SMF. By controlling the mode-field profile of the SMF with a two-step reverse-tapering method, we realize a record-low insertion loss of 0.88 dB for a SMF/NC-HCF/SMF chain at 1310 nm. Our method is simple, effective, and reliable, compared with those methods that rely on intermediate bridging elements, such as graded-index fibers, and can greatly facilitate the integration of NC-HCFs and promote more advanced applications with such fibers.
TL;DR: In this article, a plasmon resonance sensor based on D-shape photonic crystal fiber (PCF) is proposed to realize the simultaneous measurement of refractive index (RI) and temperature.
Abstract: A plasmon resonance sensor (SPR) based on D-shape photonic crystal fiber (PCF) is proposed to realize the simultaneous measurement of refractive index (RI) and temperature. The upper surface of the D-shape PCF is coated with gold film as a plasmon resonance excitation material for the detection of RI. An air hole near the fiber core is coated with gold film and filled with temperature-sensitive liquid ethanol to detect temperature. Results show that the y-polarized peaks supported only shift with RI variation and is unaffected by the temperature floating. Similarly, the x-polarized peak is only influenced by the change of temperature in the external environment. The proposed sensor achieved wavelength sensitivity of 3940nm/RIU with analyte RI between 1.35 and 1.40, and 1.075nm/°C of temperature ranging from 20°C to 60°C. The proposed liquid-filled D-shape photonic crystal fiber will have potential application in solving the problem of cross-sensitivity of temperature and RI.
TL;DR: In this paper, an extremely sensitive Photonic Crystal Fiber (PCF) based Surface Plasmon Resonance (SPR) sensor having D-shaped structure has been proposed, where gold has been used as the plasmonic material, and it has been coated outside of the fiber on its glassy surface to detect the change in the refractive index of the surrounding medium.
Abstract: In this paper, an extremely sensitive Photonic Crystal Fiber (PCF) based Surface Plasmon Resonance (SPR) sensor having D-shaped structure has been proposed. Gold has been used as the plasmonic material, and it has been coated outside of the fiber on its glassy surface to detect the change in the refractive index of the surrounding medium. Gold has been chosen as it is chemically stable and has no impact on the surrounding aqueous medium. Maximum Wavelength Sensitivity (WS) of 216,000 nm/RIU and Amplitude Sensitivity (AS) of 1680 RIU−1 have been achieved for the analyte refractive index range 1.23 to 1.42 by the proposed sensor. After conducting a detailed literature review in the relevant field, it has been revealed that the proposed sensor possesses the highest wavelength sensitivity among recently reported PCF-SPR sensors to this date. The proposed sensor also exhibits a resolution of 4.63 × 10−7 RIU and FOM of 1200. Consequently, the proposed sensor can become an ideal candidate in the field of biomedical sensing, chemical sensing, and other lower RI analytes sensing.
TL;DR: In this paper, two ultra-short polarization beam splitters based on surface plasma resonance (SPR) were designed for wavelengths of 1.31 and 1.55 μm respectively.
TL;DR: In this paper, a single air hole exposed core photonic crystal fiber (PCF) sensor based on localized surface plasmon resonance (LSPR) was proposed for bio-analyte sensing.
Abstract: Flexibility in design and controlling the wave- guide properties in photonic crystal fiber (PCF) has enabled diverse plasmonic sensing devices with attractive features. Here, we propose a novel single air hole exposed core PCF sensor based on localized surface plasmon resonance (LSPR) for bio-analyte sensing. To supports the LSPR, a gold (Au) nano strip is considered instead of continuous metal film making the proposed sensor cost-effective while experiencing low loss. A thin layer of titanium oxide (TiO2) is also used between the Au and silica glass to assist adhesion, which also contributes to enhancing the sensing performance. Considering the refractive index (RI) variation in the dielectric layer, the sensor performance analysis is carried out via finite element method (FEM) based commercially available software COMSOL Multiphysics in the visible to mid-infrared spectrum. According to numerical results, the proposed sensor shows maximum amplitude sensitivity (AS) of 1449 RIU−1 and a maximum wavelength sensitivity (WS) of 50,000 nm/RIU with a corresponding resolution of $2\times 10^{-6}$ in a wide RI range. Besides, being highly linear in sensing performance, the sensor attains low loss, with an improved figure of merit (FOM). Considering the simple architecture and competitive sensing performance, the proposed sensor could be used effectively in RI sensing applications, especially in bio-sensing.
TL;DR: In this article, a hollow core Topas-based photonic crystal fiber (PCF) biosensor is proposed for sensing in terahertz frequency range, which has the lowest confinement loss for RBC, hemoglobin, WBC, plasma and water.
Abstract: Detection of blood is very crucial as well as sensitive due to its importance in human body. In this manuscript, a hollow core Topas-based photonic crystal fiber (PCF) biosensor is proposed for sensing in terahertz frequency range. In the hexagonal cladding structure of this proposed biosensor, identical square-shaped air cavities in both the core and cladding are the building blocks. Different analytes such as red blood cell (RBC), hemoglobin, white blood cell (WBC), plasma and water are used to fill the core. The sensing features of the design will be examined using the finite element method. From the simulation results using COMSOL v5.3a software, achieved sensitivity for RBC is 99.39%, for hemoglobin is 99.27%, for WBC is 99.12%, for plasma is 99.03% and for water is 98.79% for y-polarization at optimum design conditions. In addition to sensitivity, the proposed design has the lowest confinement loss for RBC, hemoglobin, WBC, plasma and water of 1.124 × 10−15 dB/cm, 9.557 × 10−16 dB/cm, 7.242 × 10−15 dB/cm, 1.114 × 10−16 dB/cm and 2.515 × 10−15 dB/cm, respectively, in the frequency range from f = 2 to 5 THz. In accumulation to these, the design also shows negligible effective material loss, significant birefringence, enhanced effective area, large beam divergence and very low and flattened dispersion at optimum design conditions. The superior detecting capability and simple geometry of this projected PCF biosensor make it a worthy candidate for use in different practical applications.
TL;DR: In this paper, a D-shaped photonic crystal fiber-based surface plasmon resonance (PCF-SPR) sensor with linear sensing performance and a broad detection range for low refractive index (RI) liquid analytes was presented.
Abstract: We report a sensitive D-shaped photonic crystal fiber-based surface plasmon resonance (PCF-SPR) sensor with linear sensing performance and a broad detection range for low refractive index (RI) liquid analytes ranging from 1.27 to 1.37 with possible extension beyond this range. We examine three combinations of materials (silver only, graphite on silver, and graphene on silver) as plasmonic nanofilm for the PCF-SPR and demonstrate that graphene-assisted PCF has the best overall performance. We show that graphene coating of silver nanofilm improves the sensitivity and the overall figure of merit of the sensor, besides the practical benefit of protecting the silver nanofilm from surface oxidation. Furthermore, we propose two distinct ways of analyte sensing based on filling patterns where the liquid analyte can be filled internally into the top two air holes of the PCF, or externally into a rectangle channel at the top of the fiber. In the internal filling detection scheme, the graphene-assisted PCF-SPR sensor demonstrates ultra-linearity, a detection range of 0.1 refractive index unit (RIU) between 1.27 and 1.37, an average linear spectral sensitivity of 2320 nm/RIU, and a maximum amplitude sensitivity of 192 RIU−1 for 1150 nm excitation. In the external filling detection scheme, the PCF-SPR exhibits extremely large sensitivities with a maximum spectral sensitivity of 22,400 nm/RIU close to analyte RI of 1.33, and a maximum figure of merit (FOM) of 127 which is approximately five times larger than that of the similar reported PCF-SPR sensors in the literature. The combination of a broad detection range for low-index analytes, large sensitivities, design flexibility, and stability against surface oxidation renders our proposed sensor as an interesting candidate for biosensing applications in chemistry, biology, and medicine.